In recent years, increased awareness of air and water pollution problems caused by leaking gasoline or other polluting elements has focused attention on ways to detect and prevent such leaking. To this end, double-walled piping systems ("secondary containment systems") have been developed. For example, in U.S. Pat. No. 4,932,257 (to Webb), a primary pipeline carries gasoline from an underground storage tank to a dispenser, and a secondary pipeline surrounds the primary pipeline to prevent leaking gasoline from contaminating the ground.
In U.S. Pat. Nos. 4,842,163 and 4,971,225 (both to Bravo), a containment box is installed directly below a gasoline dispenser and around an impact valve assembly or around a submersible gasoline pump to collect leaks from the dispenser or pump.
In such secondary containment systems, however, it is difficult to effect repairs on the primary pipeline should a leak develop. Often, one must not only break ground around the gasoline pump, but also break up the island on which the pump is located to determine where the leak is and to fix it.
U.S. Pat. No. 4,971,477 (to Webb et al.) discloses one approach to this problem. In this patent, there is a secondary containment system with a double pipeline formed in segments. Each segment connects two access chambers which extend from ground level to below the pipeline. The ends of an outer pipeline segment connect to fittings built into adjacent chambers, respectively. The ends of an inner pipeline connect to fittings at a position located within adjacent chambers, respectively. The inner pipeline is flexible. When an inner pipeline segment or fitting is in need of repair, the covers of two adjacent chambers are removed and the fittings for the inner pipeline segment are disconnected. Then, that pipeline segment is removed from one of the access chambers for repair or replacement.
In the Webb et al. system, there must be at least two access chambers to remove a flexible inner pipe. Moreover, although Webb et al. show an access chamber below a gasoline dispenser, the patent does not disclose a way to remove the segment leading to the gasoline dispenser. One would have to remove the dispenser and perhaps even break up the island on which the dispenser is located. Moreover, Webb et al. do not address the situation where a containment box, such as in the Bravo patents, is used, and the flexible pipeline connects to a rigid line at a point below the containment box.
To allow for removal of the flexible pipeline, and to allow for adjustable positioning of the pipeline and impact valve with respect to the box and dispenser, the present inventor has created a coupling system for the flexible pipeline to the impact valve, as disclosed in copending U.S. patent application Ser. No. 07/654,952, filed Feb. 14, 1991. The system uses metal fittings and multiple bolts, but these take time to tighten or loosen and require drilling or preforming holes in the box. Accordingly, the fitting is relatively heavy, can be susceptible to leaking, and can be cumbersome to use. Therefore, there is a need for a simpler, lighter weight and more leak- and corrosion-resistant fitting.
The containment box, as disclosed in the above-mentioned Bravo patents, has an opening in the bottom or side, which connects to a vapor recovery system, to remove gasoline and gasoline fumes and return them to the storage tank. There is also an aperture in the box for receiving a conduit with electrical lines connected between the dispenser and storage tank. This aperture and the aperture where the vapor recovery system attaches to the box are potential points of leakage. Therefore, fittings to connect the vapor recovery pipes to the box and to fasten the electrical conduit with respect to the box must also provide a seal. Light-weight fittings which provide a good seal, are corrosion-resistant, and easy to use are desirable. Moreover, it would be desirable to provide a universal fitting that can be used for receiving electrical conduits or for receiving vapor recovery pipes.
In secondary containment systems, such as described in U.S. Pat. No. 4,971,477 to Webb et al. or in copending application Ser. No. 07/654,952, there is a need to pressure test the primary and secondary pipelines during the installation, during subsequent inspection, and during any maintenance, such as leakage repairs. In these secondary containment systems, underground pipelines often have junction fittings, e.g., to facilitate assembly and to facilitate repair and replacement of pipe segments. During such testing, it is common procedure to pressurize the primary pipeline beginning at the storage tank. However, even if a primary pipeline leak is detected, it is difficult to determine which primary pipe segment is leaking.